Electrical motor and dynamo brush



June 21, 1949. T. MILLER ELECTRICAL MOTOR AND DYNAMO BRUSH Filed Feb. 26, 1

.1 5 mm M v T. ;J m

Patented June 21, 1949 UNITED STATES PATENT orrics ELECTRICAL MOTOR AND DYNAMO BRUSH Tobias Miller, Cleveland Heights, Ohio Application February 26, 1944, Serial No. 524,015

2 Claims. (Cl. 171-825) This invention relates to new and useful improvements in brushes for dynamos and motors of the types which are especially useful in unfavorable atmospheric conditions of moisture and temperature, as for example in connection with airplanes, dirigibles, and helicopters when flying at stratospheric heights.

The principal object of this invention is to provide motor and dynamo brushes with a protective Jacket and insulation for protection from various climatic conditions, and for instance especially at stratospheric or such heights where low temperature tends to freeze the still remaining moisture absorbed in the lower atmosphere into small particles of ice which causes the compressed carbon brushes to crack and deteriorate. thus causing a dangerous condition and endangering flight of airplanes.

The same is hereby more fully described and claimed.

In the accompanying drawing, Figure 1 shows an armature a with insulated brushes b and connectors c. 1

Fig. 2 is a perspective view showing a brush d and a cellophane or plastic jacket c with wire I and connector 0.

Fig. 3 is a sectional view showing a brush i with wire it imbedded therein and cellophane or plastic Jacket 1 covering the entire brush with the exception of the surface I: which is exposed toward the armature a.

The construction of my improved brush for motors and dynamos is best shown in said Fla. 3. The body 1 is composed of the usual material. e. g. compressed carbon, or its equivalent such as I mphite, and to this body is applied a closely adhering plastic insulating Jacket which completely encases such body save for the end face 1: thereof which is designed to contact with the commutator or other element of the machine with which electrical contact is to be made. As indicated, cellophane, i. e. amorphosed cellulose or precipitated cellulose, as from cellulose xanthate (Fiesers OrganicChemistryJ' pages 892, 893, pub. by D. C. Heath I 00., Boston, 1944) or equivalent plastic material is preferably used to constitute such protective coating. This material, as concisely summarized for instance under the heading "Cellophane" in Gardner's Chemical Synonyms and Trade Names," pub. by D. Van Nostrand 00., New York, 1946, as a cellulose product obtained by precipitation, is not affected by moisture or oils, ls non-inflammable, and is insoluble in alcohol. The combination of this and a carbon body results in a brush which is thoroughly protected and which has an outstandingly flrm tough surface not easily abraded or penetrated. Application of the coating to the body may be effected in any desired way, but preferably in liquid form, to insure close adherence and at least a certain degree of impregnation of the body by the plastic.

I claim:

1. An electrical contact member comprising a body of conducting material including compressed carbon, and a non-melting coating of amorphosed cellulose closely applied to the surface of such body.

2. An electrical contact member comprising a body of conducting material including compressed carbon, and a coating of amorphosed cellulose bonded onto such body except at one end.

TOBIAS MILLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 428,742 Brush May 27, 1890 447,352 Rice Mar. 3, 1891 573,105 Raymond Dec. 15, 1896 1,959,848 Abbott May 22, 1934 2,095,800 Elsey Oct. 12, 1937 2,174,887 Kiefer Oct. 3, 1939 2,224,724 Elsey Dec. 10, 1940 FOREIGN PATENTS Number Country Date 488,294 France June 18, 1918 

